Thermo-electric generation.



J. D. TAYLOR. THERMO ELECTRIC GENERATION.

APPLIGATIOEI FILED MAR. 27, 1907. RENEWED JAN. 18, 1909.

Patented Nov. 30, 1909.

2 SHBETS-SHEET l.

W I T NE SSES .J. n. TAYLOR. THERMO ELECTRIC GENERATION. v APPLIUATIORFILED MAR. 27, 1907. RENEWED JAN. 18, 1909. 941,82. Patented Nov. 30,1909.

2 SHEETS-SHEBT 2.

f R97 0 b"a c d I WIT ESSE a' c; d [NVE N TOR.

JOHN D. TAYLOR, OF PITTSBURG, PENNSYLVANI w g E THERIvIO-ELECTRICGENERATION.

SMLSQS.

Specification of Letters Patent.

Patented ho v. 30,1909.

Application filed March 27, 1907, Serial No. 364,771. Renewed January18, 1909. Serial No. 472,996.

To all whom it may concern:

Be it known that I JOHN D. TArLou. ct

I P1ltSbl1l". Alle hen count Perms 'lvama. 2:. z: y ya have invented anew and useful lm'n'ovemeat in Thermo- Electric Generation, 0: which thefOllOWID 1s a tull, clear, and exact description, re erence being bad tothe accompanying drawings,

Figure 1 is a vertical section, or sectional end-elevation, of one formof thermo-electric generator embodying my invention; Fig. 2

1s a longitudinal vertical section of the same; Figs. 1 and 2 are detailviews showing a modification; Fig. 3 is a developmentot a portion of thedrum commutator; Figs. 4 and 4C are detail views showing one mode ofconnecting the elements; Figs. 5 and 5 are similar views showing anotherway of connecting the elements; and Figs. (3 and 7 are dis. ramshereinafter more fully described.

I y invention is based on the discovery by Seebeck that, if in a closedcircuit of two metals, the two junctions of the metals a re at diiterenttemperature an electric current will flow around the ci cuit, and thediscovery by Peltierthat; it a current flows .across the junction of twometals III'OIIQ direction, heat is absorbed, while it it flows in theopposite direction, heat is liberated. Up to the present time nopractical application of these discoveries has been made to thegeneration of electric current for power purposes, iicr the reason thatall the thermoelectric generators that have been devised,

have been so very inefiicient that they canand' in the accompanyindrawings which substances.

form part thereof, ully describe and illustrate a praetical'nieans forconverting heat directly into electricity.

The principal losses in the thermoelectric generator as it has beenheretofore constructed, are. due to the ra id conduction of heat, asheat, through the substances of which the generator is composed, from.the hot junction to the cold junction, where it must be disposed of byradiation or otherwise; and to the generation of heat by the current inovercoming the resistance ofthe The first could be reduced by makingthe'el'ements veryflong, thus reducing the slope of the temperature; thesecond,

" by making the elements very short, which forming part of s e I V thisspecification, in wh1ch ing the means for reducing these losses to amininuun, and to construct a thermo-electrio generator which shallcomparefavorably in oiiiciency wilh'other forms of heat motors. laccomplish this object by taking the junction through a recurring cycleof four operations: First, the junction is heated to the upper limit oftemperature by passing the electric current through it in ,the directionto liberate heat while the junction is inclosed by insulating materialto prevent escape of heat. Second, the current is then reversed andsentthrough the junction in the direction to absorb heat, but thetemperature is maintained substantially constant by placing the junctionin a hot chamber wherein heat absorbed by the current is replaced byheat received from the hot chamber. Third, with the current stillflowing in the direction to absorb heat the junction is then passedintoan insulating chamber, wherein the absorption of heat by the currentresults in reducing the temperature to the lower limit. Fourth, thecurrent is again reversed and sent through the junction in the directionto liberate heat and at thesame time the junction is passed into a coldchamber wherein the temperature is maintained substantially constant bythe heat being carried off by the cold chamber. Opposite junctions ofeach element are, of course, passed through opposite steps of the cycleat the same time. The principle upon which this cycle of operation isfounded is very similar to that enunciated by Carnot for the fluidpressure engine,--a.principle which houstbe closely adhered to forsecurgreatest upon the fluid, and its temperature is raised.

from the lower isothermal AD to the upper isothermal l --Ihe curve B- -Crep possible etliciency in any 'form of heat engine whatever.

lei

resents the isothermal expansion of the lluid during which work. is doneby the lluid on the piston, and its lei'nperature is kept constant byheat received from an exlernal source. The curve C-D ri'niresents theadiabatic expansion d uringwhich work is done by the fluid, and itstemperature is reduced from the upper to the lower working limits. Thecurve D A represents the .i.--:ol;l|ern1al compression of the lluidduring which work is expended on the .lluid, and its lltlllljflil'iltlllfi is maintained constant by rejecting the heat liberated tothe re l'rigeralon- .ln liio'. l lhe line i i- B represonls the periodduring which the current healiilg {he unction and raising ilstenlpcrature from the lower isothermal [hf-'1) to the upperisuiiilnirnial E'C. The line ll--C represents the period during whichthe (illll'l'l'lli is ebnorbiiur heat at the junction, which heat issupplied by the hot chamber, thus maintaining the leniperature constant.The line i ll) re nfcsents the period during which the current absorbsheat and reduces the temperature of the junction from the upper to thelower isothernml. The line D- ii. represents the period during which thecurrent libel-ales heat which is rejected to the cold clminber and thetemperature thereby maintained constant. 'lhe areas 11 .i l el and [1 llll u represent work done by the current and are to be reckoned IlUdllW). The areas 0 ll ll r: and. C l) d Iftlln'lfrlllll bent transtermed into electricity, and are to be reckoned positive. Thedi'll'crcnce between the positive and new ative areas, or the area i l.ll (I ll, represei .i the amount oi. useful work done, or, -in otherwords, the amount of elccl rical energy developed and avnilaliile foruse in the external circuit. lhcnq 1parent difference in the twodiagrams, (Figs. 6 and 7),.is due to the fact that the ordinalesrepresent quanl ities of dilferent kind. in Fig. [5 the rerl iealordinates represent pressures and the horieontal ordinates representvolumes; in l igr. 7 the Vertical ordinates represent eleclro motiveforces and the ln'n'iarmtal ordinates I represent Quantities of electrity. do lhe electro-motive force at a ju:= .;ioir1 in row stant whilethe linnperaturo ieniains constant,tl1e isolliernm ls are horizontalstraight lines, While in llfigg. (l, as is well lnnnvn, theisotliernials are equilateral hyperoolus.

The diagrams Fig. 6 and Fig. l are theoretical and are never realized inpractice. The diagram of my thermoelectric gen- :i' ntor would perhapsnot approach any closer to that 01" Fig. 7 than the diagram of the bestfluid pressure engine approaclws that of Fig. 6. In p notice theding-min has its corners rounded oil, and more nearly resen'ililos anellipse than the lie-ur slmwn in Fig. 7..

'lhere are two hind i otlf los es inrurml in l the oporatioi'i of allheal l en ines: one n lhe l oanrlao heat rejected at the lower limit oftemperature, and the other is the heat conducted away and radiated bythe parts of the engine. The first cannot possibly be avoided, as toavoid it requires the lower working limit. of temperature to be at theabsolute zero which cannot be attained in practice. The second can beminimized by proper mnwlrlnrlion and methods of operation. To lhe secondclass belong the losses, mentioned above, incurred in the operation ofthe lilllf'l'lIJU'OlUfZtI'lU generator as heretofore con z-zlruclcd andwhich it is the object of this invenl ion to reduce to a minimum.

l igj. 1. shows a sectional end elevation, and Fig.5. 2 a sectional sideelevation of a n-el'erred .l'orni of my lLlIBL'IHO-GlfifltllC encralorrinlnulyino my invention. lhc lhermo-cleolrio cements are arranged inrows, and these rows are arranged in the form of a drum with the rowslying parallel lo the axis of the drum and suitably inh'illlll'l'll fromeach other. The drum thus 'lfornied is supported on the spiders 25 and2b, which are supported by and are free to relate on the journals 3].and 32 respectively. The j ournals ill and 32 are supported by thepillar. E30 and 30 respectively, which project upwardly from the basell). Attached to the spid r 25 is the worm Wheel 20, nieshingwitlilllt'. screw 2], which may be driven by a bllllll electric i'lioltor, orother means, (not shown), For he purpose of slowly rotating the drum. itcylindrical shell divided into the (Ullll)llllillltllllfl 8, 10, 11 and14; surrounds the rotatable drum, and is fixed to the base In. Thecomparti'nents 8 and 10 oi the shell contain insulating material (1,preferably .wsbcslos, for the purpose of preventing the interchange ofheat between the thermo electric junctions adjacent thereto and the airor other surrounding objects. The comparlnu-nt ll is the one in whichthe junctions receive heat from a source of heat while the junctions arepassing by the compartment. "lh'e source of heat may be a gas llanw, thegas beingled in tln'olwh the pipe 1. and the burned gases escaping bythe pipe 5'. The part of the shell forming the coinparlnlent ll has ribsprojecting, from its inner surface, for the purpose of deflecting llielianle dowi'nvardly against the junctions. The compartment 14 is the onein which the rejected heat inearried awn from the junctions. Thisina'fi'me efiecte by a current of cold air blown in through the pipe 4and out at the opposite end of the compartment. The compartment 14 alsohas ribs projecting from its inner surface, for the purpose of causing:the curre of air to impinge against the junctions. 'lbese ribs may, ifdesired, be replaced by pipes through which cold water is licplcirculating as shown at 14", in Figs. 1" and Li. ii similar shelldivided into imilar mimoarluientsis placed within the senses I rotatabledrum and supported by spiders 27 131 and 32 respectively.

compartment 12, is led in throu aiidQS fixed to the inner ends of thejournals 12 is the cooling compartment; 13 1s the heating compartment,and 7 and 9 are the. insulating compartments, of this inner shell. Theair pipe 2, through which an is blown for cooling the gh the ourna-l 32,which is hollowed out to receive it. The gas pipe 3 is led in throughthe air pipe 2. The pipe 6 for the escape of the burned ases jasses outthroli h the hollowournal g l J zbars of the commutator 22 in much thesame '-n1utator.

nected in two separate and independent M lator type.

i and so on throughout the series.

connecting strip attached to the last element 3 1. The inner series 0?con'ipartments are so located relatively to the outer series of coipartments, that opposite junctions of each element, are, at the sametime, passing through opposite points or operations of the cycle.

Therows of elements are connected together electrically, and connectedto the manner as theconductors on the armature .of the well knownmagnetoelectric generator] Fig. 3 shows a development on a plane surfaceof a part of the drum with its rows of elements, and a part of the com-The rows of elements are conseries. This is done to avoid the shortcircuiting of two rows when the collecting 'hne bar to the next.Substantially this same method of coi'inection is employed in somealternating current motors of the commu- The brushes are made slightlynarrower than one bar of the commutator, so as not to touch, three bars.at one time. 23 and 24 representbrush holders'by way of which thecurrentv enters and leaves the series of elements. The arrows clearlyshow the direction of flow of the current.

Fig. 4; is a view showing in detail a pair of junctions and a method ofjoining the elements together. The elements 36 and 3'? are riveted andsoldered or brazed, or otherwise securely connected to the ribbed plateThe plate 38 should be made of a material that is a good conductorofheat for the purpose of rapidly carrying heat to and from its junctionwith the elements 3% and 37. The element 36 is joined at its oppositeend by a similar-ribbed plate 39 to another element of the same materialas 37, i0 is a in a row for the purpose of connecting it with anotherrow or with a bar of the commutator.

It. the specific electrical. resistances of the elements are different,the minimum total resistance with the minimum space occupied will besecured by making the area of the cross section of the elementsproportional to their respective specific resistances. .Fig'. '5

shows a form of construction suitable to the case where the specificresistance of the ele which has just entered the heating chamber 11after having passed through the insulating chamber 10, wherein itstemperature was raised by the passage of the current. 16 is a junctionopposite 15, which has just entered the cooling chamber 12 after havingpassed through the insulating chamber 9 wherein its temperature waslowered by t-l passage of the current. The current through thesejunctions was reversed. atthe time of their entrance into the chambersll and 12 respectively, and is flowing in the direction to absorb heatat the junction 15 and liberate heat at the junction 16. Before the heatreceived from the hot chamber 11 has time to flow more than a short distance into the elements joined. at 15, this junction will pass out ofthe chamber 11 into the insulating chamber 8, wherein heat is stillabsorbed by the current and the temperature of the junction therebyreduced so that heat that may have passed into the elements will flowback toward the junction and be absorbed by the current. Junction 15then passes into the chamber 14, at which time the current is reversed,but the temperature oi"- the junction is maintained subs stant-iallyconstant by the abstraction of heat. The junction 16 in the mean timehas passed into the chamber 13, where its upper limit of heat is beingartificiaily ,maintained. After the machine has been in operation forsome time, the temperature at the middle point of an element will be amean between the highest and lowest temperatures of the junctions, andthere will thereafter be no interchan e of heat between the middlepoints of t e elements and other pat-ts of the machine. The tempera.tures of the junctions and ad'aoent parts of the elements will rise andfat in accordance with the direction of low of current, and theirposition with reference to the heatin and the cooling chambers By thismethod of operation I am enabled to make the ele-' ments very short, andthus reduce their electrical resistance to a very small quantity. Atthesame-tirhe heat is not allowed to escape by conduction, as thecurrent is given opportunity vt'oabsorb it before it has time topenetrate'very far into the elements. The electro-motive force of asingle pair-of elements is, of course, small when compared with othersources of electro-mo'tive force,. but this has nothing to do withefiiciency. The etiiciency of a one hundred vo'lt motor may be just ashigh as that of a ti e hundred volt motor. H Any sired electromotiveforce may be obtained by joining enough elements in series, and anydesired current carrying and generating capacity may be obtained bymaking the cross sections of the elements large enough. The frequentreversal of the current through the junctions has a tendency to preventdeterioration, because a current in agiven direction will undo thatwhich has previously been done by an equal current in the oppositedirection.

My invention is susceptible to various changes by those skilled in theart. without departing from its spirit and scope. Thus, the elements maybe arranged and connected in various ways; the turn] of the movablecarrier therefor may he changed, as may also the arrangement of theseveral. compartments for controlling the temperatures of the junctions;various means may be eu1- ployed for applying external heat to andabstracting heat from the junctions, and various other modifications maybe made. The elements may consist of any suitable metals or alloys, andmay be oi various forms and connected with each other in various ways.

Nhat I claim isz- 1. The herein described method oi. thermoelectricgeneration, which consists in periodically reversing the current througheach lllPl'llltlOlll'll'lll junction to thereby alternately raise andlower the temperature oi. the junction to its upper and lower limits,and alternately su iplying heat toand ex tracting heat from the junctionafter each current reversal to maintain the temperature efl eeted by thecurrent prior to the reversal; substantially as described.

2. The herein described method of thermoelectric generation, whichconsists in periodically reversing the current through eachthermo-electric junction to thereby alternately raise and lower thetemperature of the junction to its upper and lower limits, andalternately supplying heat to and extracting heat from the junctionafter each current reversal to maintain the temperature cifected by thecurrent prior to the reversal, one junction of each element being cooledwhile its other junction is being heated; substantially as described.

3. The method of thermo-eleet-ric generation, which consists incontrolling the current generated by the thermoelectric elements tocause it to alternately (low in opposite directions through thejunctions of said elements to thereby alternately liberate and absorbheat, and maintaining, intermediate the current reversals, substantiallythe temperature produced at the junctions by the action of the currentprior to the reversal; substantially as described.

4:. The method of thcrmo -eleetrie genera.- tion, which consists incontrolling the current generated by the thermt'i-elcctric eleet ane tothereby alternately liberate and absorb heat, and alternately applyingexternal heat to and abstracting heat from the junctioi'is to maintaintemporarily the unctions at substantially the ten'iperatures produced bythe current; substantially as described.

5. The herein described method of thermoelectric gcneration, whichconsists .in first heating a thcrmo-clectric auction by causing thecurrent to flow therethrough iii a direction to liberate heat and raisethe temperature of the junction to its upper limit, then reversii'ig thedirection of flow of current to cause it to absorb heat from thejunction, and replacing the heat so absorbed by external heat tomaintain the junction at a substantially constant temperature, thencausing the absorption of heat by the current to reduce the temperatm'eof the junction to its lower limit, and finally again reversing thecurrent How and cooling the junction to maintain its lower temperhture,these operations being repeated in a recurring cycle; substantially asdescribed.

6. The herein described method of thermoelectric generation", whichconsists in first heating one junction of thermo-eleetric elements bycausing the current to flow there through in a direction to liberateheat and raise the temperature of the junction to its upper limit, thenreversing the current to cause it to absorb heat from the junction, andreplacing the heat thus absorbed by external heat to maintain thejunction at a substantially constant temperature, then causing thecurrent to absorb heat from the junction to reduce its temperature toits lower limit, and finally again reversing the current and cooling thejunction to maintain its lower temperature, these operations beingrepeated in a recurring cycle, the two junctions of each element passingsimultaneously through opposite steps of the cycle; substantially asdescribed.

7. The method of thermo-electric chem tion, which consists incontrolling t e cur rent generated by the thermo-electric elements tocause it to alternately liberate and absorb heat at the junctions of theele- 1nents,ai1d alternately applying external heat to the heatedjunctions and-abstracting heat from the cooled unction to temporarilymaintain the temperatures effected b the current at times when thecurrent 18 affooting the temperature of the junctions- 'lOO in acontrary direction; substantially as 1W described. i j

8-. The method of thermo-electric enemtion, which consists in firstheating at ermoelectric junction by ausing the current to (lowthercthrough in a direction to liberate heat and at the samel timeinsulating the unction to numnuzeithe escape of heat eanaae therefrom,then reversing the direction of current flow to cause it to absorb heatfrom the junction, replacing the heat so absorbed by external heatapplied thereto, then causing the absorption of the heat by the currentto reduce the temperature of the junction to its lower limit, andfinally again reversing the current and cooling the junction to maintainits lower temperature, these operations being repeated in a recurringcycle; substantially as described.

9. In thermo-electric generation, the step which consists in alternatelyreversing the fiow of current through the junctions of thethermo-electric elements to alternately raise and-lower theirtemperatures; substantially as described.

10. In thermoelectric generation, the method which consists inalternately reversing the flow of current through the junctions toalternately raise and lower their temperatures, and in temporarilymaintainin substantially constant the temperatures eiiected by thecurrent prior to each reversal by the application of external heatingand cooling means substantially as described.

1'1. The method of thermoelectric generation, which consists incontrolling the current generated by the thcrmo-electric elements tocause it to alternately absorb and liberate heat at any given junction,applying external heat. to the junction when heat is being absorbed bythe current, and ab stracting heat from the junction when heat is beingliberated by the current, substantially as described.

' 12. A thermo-electric generator having a plurality of connectingelements, means for reversing the direction of current flow through thejunctions of the elements, and means for applying and extracting heatfrom the junctions at recurring intervals; substantially 'as described.

13. A thermo-electric genera-tor having a plurality of connectedelements, means for reversing the direction of flow of current throughthe junctions of the elements, and means for applying heat to eachjunction after one current reversal and for extracting heat therefromafter each opposite toversal; substantially as descibed.

14. A thermoelectric generator having a plurality of connected elements,means for reversing the direction of current flow through the junctionsof the elements, and means for maintaining the temperatures efmy hand.

fected by the current low while the latter is acting in a direction tochange such tcmperatures; substantially as described.

15. A thermo-electric generator having a plurality of elements, and acommutating device to which said elements are connected in independentseries; substantially as described.

16. A thermo-electric generator having a plurality of connectedelements, a rotary device to which the elements substantially asdescribed.

17. A thermo-elcctric generator having a rotary carrier, a plurality ofthermoelectric elements mounted thereon, a current commutating device towhich the elements are connected, and means for applying heat to andextracting heat from the junctions of the elements; substantially asdescribed.

18. A thermoelectric gci'ierator having a. plurality of elements, arotary carrier for the elements, and chambers or compartments adjacentto the carrier and provided with means for aifecting the temperatures ofthe elements; substantially as described.

19. A thermo-electric generator having a plurality of elements, rotarycarrier upon which said elements are radially mounted, and two series ofchambers or compartments respectively adjacent to the opposite junctionsof each element. and provided with means for changing the temperaturesof the elements; substantially as described.

20. A thermoelectric generator having a rotary carrier, a plurality ofradiallyara re connected ranged elements mounted on said carrier,

rounding the carrier, and other heating and cooling compartmentsarranged inter-ionic of the carrier, some of said chambers haviheat-insulating means; substantially as scribed.

In testimony whereof, I have here-nnteset JOHN D. 'lAi'L l llt.

l Vitnesses GEO. B. .BLEMING, Geo. H. PARMELEE.

carrier therefor, and a-current commutating I

